Method of making composite fireproof acoustical tile



H. w. HEINE 2,791,020

METHOD OF MAKING COMPOSITE FIREPROOF ACOUSTICAL TILE May 7, 1957 Original Filed April 12, 1951 INVENTOR Henry WI H43 H18 United States Patent METHOD OF MAKING COMPOSITE FIREPROOF ACOUSTICAL TILE Henry William Heine, Washington, D. C.

Continuation of application Serial No. 242,774, April 12, 1951. This application June 29, 1953, Serial No. 364,590

1 Claim. (Cl. 25-156) acoustical purposes; however, such tile to be acoustically efiicient and sound absorbent, must, structurally, be relatively soft or unfused as distinguished from fused or vitrified and therefore, is fragile and readily breaks,

crumbles, or chips when handled unless exceptional care is used from the time it is made until'the time it is in- I stalled.

Attempts have been made to improve the physical strength of tile of this type, especially in enclosing all or a portion of the relatively soft sound-absorbing body with a comparatively thin, hard vitreous skin or surface. However, this type of protection has not proved successful because the surfacing material enters the voids during application and materially reduces the sound absorbing efiiciency of the completed tile due to closing or partial closing of all or some of the voids or openings.

Other types of reinforcement have also been tried but so far as is known, none of them have been successful on a commercial scale and the acoustical ceramic tile are today follows largely the pattern of producing simply a relatively soft sound-absorbing body with voids or interstices which is relatively fragile and, therefore, often costly from the standpoint of handling and installation.

Accordingly, a primary object of the invention is to provide a composite acoustical tile having a permanent, relatively soft, sound-absorbing body containing a multiplicity of intercommunicating voids formed by burning out carbonaceous material, and a face, or faces, sides and ends, with a hardened porous surface wherein the pores are maintained open during the firing process to insure communication between the voids or openings of the hardened surface and the relatively soft, sound-absorbing body.

Another object of the invention is to provide a method or methods to produce tile of the type set forth which lends itself to performance on available equipment thereby providing a tile which is competitive commercially with other types not having advantages of the present tile.

By way of example, the product of the invention is shown in the accompanying drawing, in which:

The figure is a perspective view of a tile made in accordance with this invention;

As will be observed from the drawings, the tile of Figure 1 includes a relatively soft porous acoustical body A and a relatively hard or vitreous portion B, the same resulting from firing the same tile at different temperatures.

In general, the process of this invention comprises 2,791,020 Patented May 7, 1957 "ice preparing a mixture of ceramic material and a carbonaceous material. Any ceramic material may be used, including any of the various potters clays or fire clays. Among the usual ceramic clays are shale, diatomaceous earth, silicate clay and kaolin. The carbonaceous mate rial may be the usual materials which can be reduced by burning, such as wood chips, coal granules, either bituminous or anthracite, bagasse, corn cob granules, cellulose fibers, and the like.

The ceramic material is thoroughly mixed with the carbonaceous material and the mixture formed to the sizes and shapes desired, such as of standard tile pieces. The proportions of ceramic to carbonaceous materials may vary in each case and will depend upon the percent of voids desired in the final product. For ordinary purposes, however, a proportion of substantially 50 percent ceramic material to 50 percent carbonaceous material, by volume, is satisfactory. It is to be understood, however, that no specific proportion is critical and the invention is applicable to all relative proportions of ceramic and carbonaceous material.

The formed pieces are then water smoked. The water smoking temperature will vary with the particular type of ceramic material used but will usually be in the range of about 250 to 600 F. The heat is applied until substantially no further steam can be driven ofi.

The water smoked pieces are then baked to a salmon texture at a higher temperature. For most ceramic clays this temperature should be in the range of about 1200 to 1500 F. During this baking period the carbonaceous material burns out and leaves a friable, fragile, light porous structure. The nature of the reaction is such that the voids of the structure connect with each other, that is, they are intercommunicating.

The baked material is then cooled to about F. and one or more surfaces thereof are coated with a thin layer of difierent ceramic material, such as kaolin, admixed with a coloring matter and a carbonaceous material. The thin layer should have a thickness of about ,5 to 9 8 of an inch. The ceramic pieces are then processed through the stages of water smoking and baking as indicated above and finally subject to the fiuxing temperature until the added layer becomes fluxed. The withdrawal to a sub-fiuxing temperature followed by cooling is then effected.

The effect of the fiuxing is to develop a hardened surface layer without substantially affecting the acoustical properties of the tile developed by the burning out of the carbonaceous material. In other Words, by fiuxing only a thin surface layer of the baked ceramic material, either as such or in the form of an added layer, and quickly cooling it, the interconnecting voids are maintained and, at the same time, the tile is strengthened at the surface, thereby providing an acoustical tile that is resistant to chipping, cracking and breakage generally.

The procedure in which a surface layer is added before fiuxing is particularly useful in cases where it is desired to prepare tile with colored surfaces for decorative purposes. It also permits better control of the depth of fiuxing by using as the surface layer a ceramic material having a lower fiuxing temperature than the filler ceramic material thereby preventing excessive fiuxing beyond the thickness of the outer layer.

The following example will disclose the manner in which the invention may be practiced but it is to be,

understood that these examples are given by the way of illustration only and not by way of limitation.

Example Wet potters clay is thoroughly mixed in equal volumetric proportions with A" to /2" granules of a bituminous coal in a pug mill and extruded therefrom in the form Theembryo tile. is heatedingtheifirst or watersrnokingchamber to, a ;temperature :of 400 to 550, F; until steam ceases;.;to ;;issue.- The, pieces, are :then. gradually brought. to astemperaturetofflwo tosl500i F. in themextgor burning; chamberrandj maintained therein until. the; care bonaccousimaterialiis burneckout and the. clay baked to, a softrsalfilonttcxture.

The tile pieces are then removed from,.the;kiln and; co0led;to;-,artemperatureiofuabout.110? F. To selected surfaces. ofirthetilepieccs there ;is,,applied, to to; /e.'-'

layemof rolled; kaoliniadmixedswith; coal. granules, in; equalsvolumetricproportions, ancLa pigment. The .piecesaresrthenrreprocessed isto, water ;srnoke -the;.-applied, layers andzthenrbaked to a soft. salmon ,texture as, in;the;case.

of::the-;basic or filler clay material. The baked-layers 20 acoustical tile having an unfusedbody providedrwith a.

multiplicity of intercommunicatingrvoids. and .a relatively hard. coating or surfacing also, having a, multiplicity, of' voids communicating with each otherand also with they voids. of: the body, the coating addingstrength torthe body while preservingatheaacoustical efficiency of the.

entirewtile. I. claim: A; method; of manufacturing: a composite acoustical tile, comprising, uniformly mixing a ceramic material with ,a carbonaceous material, forming the resulting mixture into a desired shape, heating the material at a temperature and for a period to effect water smoking thereof, heating the resulting water smoked material at a temperature and for a sutficient period to cause the ceramic material to become baked and the carbonaceous material to become burned and thereby result in the :development of a plurality of intercornmunicating voids in the baked material, cooling the material and applying to exposed'surfaces ofxthe baked material a thin layer of a different ceramic material admixed with a carbo' naceous material, ,heating the resulting body to effect Water smoking of the freshly applied layer'followedby further heating to bake the layer and cause the carbonaceous material ,thereintotbecome burned and result in the development of a plurality of voids communicating with the voids of the previously baked ceramic material,, subjecting thebaked surface layers to heat at its fluxingtemperature and maintaining it in contact therewithuuntil said layer becomes fluxed and then promptly removingthe material to a temperature below the fluxing point.

References Cited in the file of this patent UNITED STATES PATENTS 1,742,515, Mandell Jan. 7, 1930 1,925,985 Coss Sept. 5, 1933 1,941,804 Kern, Jan. 2, 1934 1,999,371; Parsons Apr. 30, 1935 2,008,718 Jenkins; July 23, 1935 2,124,086; Slidell; July 19, 1938 

